1. Field of the Invention
This invention relates to a lithium aluminum complex hydroxide salt (to be abbreviated as LAHS) and preparation thereof and more specifically, to a LAHS useful for a stabilizer having an excellent heat stabilizing action for chlorine-containing polymers or olefin-type resins containing halogen-containing catalyst residues.
2. Description of the Prior Art
Chlorine-containing polymers such as a vinyl chloride polymer are colored by a heat decomposition reaction such as dehydrochlorination or are liable to decrease in mechanical properties in a heat molding processing and heat histories subjected thereafter, and to prevent these defects, the compounding of stabilizers is generally necessary.
Olefin resins produced by using Ziegler-type catalysts contain halogen-containing catalyst residues, and these residues generate hydrogen chloride during a heat molding processing to form rusts in a molding machine, or cause deterioration of resins such as yellowing. To remedy these defects, it is widely practiced to incorporate stabilizers for capturing hydrogen chloride.
As such a stabilizer, the use of hydrotalcite has been known from old. For example, Japanese Laid-Open Patent Publication No. 80445/1980 describes the use of hydrotalcite as a stabilizer for halogen-containing resins. Furthermore, Japanese Patent Publication No. 36012/1983 describes the compounding of a .beta.-diketone compound and a hydrotalcite represented by the following formula EQU Mg.sub.1-x.Al.sub.x (OH).sub.2.A.sub.2/2.mH.sub.2 O
wherein x is a number of 0&lt;x.ltoreq.0.5, A is CO.sub.3.sup.2- or SO.sub.4.sup.2-, and m is a positive number, PA1 wherein M is Mg, Ca or Zn, A is CO.sub.3 or HPO.sub.4, x, y and z are positive numbers, and a is zero or a positive number, PA1 wherein m is zero or a positive number, PA1 wherein X is an inorganic or organic anion, n is a value number of anion X, and m is a number of not more than 3,
in a halogen-containing resin.
Furthermore, Japanese Patent Publication No. 30737/1984 describes the compounding of at least 0.01% by weight of a complex compound having the general formula EQU M.sub.x Al.sub.y (OH).sub.2x+36-2z (A).sub.z.aH.sub.2 O
in a polyolefin containing halogen-containing catalyst residues produced by using Ziegler-type catalysts.
Hydrotalcites are complex hydroxide carbonate salts of magnesium and aluminum and non-toxic, have excellent thermal stability, and are characteristic in that they are transparent when incorporated in polymers.
Hydrotalcites ideally have a chemical composition represented by the following formula EQU Mg.sub.6 AL.sub.2 (OH).sub.16.CO.sub.3.mH.sub.2 O
but Mg and A1 within a broad range tend to form a solid solution as shown in the formula shown in the above prior arts cited above. It is difficult to produce a product having a fixed composition.
Clays and Clay Minerals, Vol. 25, pages 384 to 391 (1977) gives a thesis entitled "Crystal-Chemical Study of Layered (Al.sub.2 Li(OH).sub.6).sup.+ X.sup.-.nH.sub.2 O" by C. J. Serna et al. which describes the synthesis of a lithium aluminum complex hydroxide salt by adding a benzene solution of aluminum-tri- (sec-butoxide) (ASB) dropwise to an excess of lithium carbonate aqueous solution to hydrolyze ASB, washing the resulting gel and hydrothermally treating it at 130.degree. C. for several days. Journal of Solid State Chemistry, Vol. 60, pages 283-288 (1985) also gives a thesis entitled "Anion Intercalation and Exchange in Al(OH).sub.3 --Derived Compounds" by I, Sissoko et al. which describes the formation of LAHS by adding AlCl.sub.3 dropwise to an aqueous solution containing LiOH and Na.sub.2 CO.sub.3, changing the pH from 13 in the early period to 10.2 in the final period to form a gel-like precipitate, and ripening it with stirring (see Comparative Example 1 which appears later).
However, LAHS synthesized by these known methods is a gel-like particle and the growth of the crystal is still insufficient. In addition, the shape and size of the particle are irregular, and the resulting LAHS is still insufficient for application of compounding agents to resins.